Courts often apply rules of evidence that permit an expert witness to base opinions on facts that are not within the expert’s personal knowledge — that is, facts the expert did not acquire through personal experience or observation — if the facts are “of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates.” The rule allows experts to testify about hearsay that would otherwise be inadmissible.
Does the rule allow experts to testify about any fact that the expert relies upon, simply by claiming that experts in the field routinely rely upon facts of that type? Too many courts answer “yes” to that question. The California Supreme Court recently explained how limitations to the rule affect the testimony that a “gang expert” may give in a criminal prosecution.
Gang Crimes in California
California law makes it a crime to be an “active participant” in a criminal street gang. The law also enhances penalties for felonies that are committed as a “criminal gang activity.”
To convict a defendant of participating in a street gang or to obtain enhanced penalties for a felony charge, the prosecutor must prove beyond a reasonable doubt that the defendant actively participated in a criminal gang with the knowledge that the gang’s members engage or have engaged in a pattern of criminal gang activity. The prosecutor must also prove that the defendant assisted or promoted the gang’s commission of a felony.
California law defines a “criminal street gang” as a group of three or more people if the group: (1) is identified by a common name or symbol, (2) commits specified crimes as a primary activity, and (3) whose members engage or have engaged in a pattern of engaging in criminal gang activity. A “pattern of criminal gang activity” means to commit two or more specified crimes at separate times within three years of each other. Courts refer to those earlier crimes as “predicate offenses.”
Facts of the Case
Two men were sitting on the tailgate of a truck at a carwash in Arvin. Shots were fired in the direction of the two men. A bullet struck the leg of one man. An officer in a nearby patrol car saw another pickup truck driving slowly past the carwash. The officer saw flashes from the pickup truck that coincided with the sound of shots fired.
The officer chased the truck and eventually arrested its two occupants. Jose Luis Valencia was driving and Edgar Isidro Garcia was in the passenger seat. The officer saw Garcia throw something from the vehicle. A cylinder from a revolver was later found in the vicinity where Garcia threw the object.
The two men were charged with a variety of crimes, including attempted murder and committing a drive-by shooting. They were both charged with active street gang participation. The prosecution also sought street gang sentencing enhancements for the other felonies.
To prove that the defendants belonged to a gang that had engaged in a pattern of criminal gang activity, the prosecution relied on the testimony of Arvin Police Officer Ryan Calderon as a gang expert. Calderon claimed expertise because he had “personally investigated about 200 crimes involving the Arvina 23 gang.”
Calderon testified about monikers, graffiti, tattoos, colors, and territory that he associated with the Arvina 13 gang. In Calderon’s opinion, Valencia and Garcia were members of the Arvina 13. Calderon based that opinion on their tattoos and police contacts.
Calderon testified that the shooting in which Valencia and Garcia engaged benefitted Arvina 13 by “creating community fear and gang notoriety.” Calderon identified three predicate offenses committed by alleged Arvina 13 gang members: assaults in 2008 and 2010 and an attempted robbery in 2013.
Calderon had no personal knowledge of the predicate offenses. He did not investigate those crimes. Rather, he learned about them “from conversations with other officers and a review of police reports.”
Admissibility of Gang Expert Testimony
Most courts allow gang experts to testify, despite the doubtful admissibility of their testimony. Police officers are trained to enforce the law, not to make sociological determinations. They often cherry-pick their facts and support their opinions with no identifiable methodology, much less one that is clearly reliable.
Despite the dubious nature of gang expert testimony in general, the California Supreme Court reviewed the convictions of Valencia and Garcia to address a narrow question. The defendants argued on appeal that Calderon was not entitled to base his opinion on facts about which he had no personal knowledge.
To prove that members of the gang to which the defendant belonged committed at least two predicate offenses within the statutory timeframe, prosecutors must generally present evidence “of who committed the crime and when they did so, as well as evidence of their gang membership and the nature of the crimes.”
The prosecution argued that Calderon was entitled to rely upon hearsay to form opinions if other experts in the field would generally do so. The prosecution contended that the hearsay testimony was admissible because it was not offered to prove that what the officer was told was true, but to establish the basis for the officer’s opinions. Of course, if the facts are not true, they have no value and no expert should consider them.
Hearsay and Expert Testimony
The rule that allows experts to testify about facts that are generally known to people who share a field of expertise — facts acquired in school or professional training and by reviewing research conducted by other experts — recognizes the impracticality of requiring experts to have personal knowledge of all the facts upon which they rely. Scientists rely upon the conclusions of experiments without performing those experiments themselves. It simply isn’t possible for experts to acquire all the facts from personal experience that they glean from reading journal articles or by listening to other experts speak at professional seminars.
California courts thus draw a distinction between general facts that are part of the expert’s base of knowledge and facts that are specific to the case in which the expert testifies. Case-specific facts must be established by witnesses who have personal knowledge of those facts. In criminal cases, allowing an expert to give hearsay testimony about case-specific facts might violate the defendant’s right to confront the witness who supplied those facts, because that witness is not subject to cross-examination.
Experts can rely on case-specific hearsay if a witness with personal knowledge testifies that the facts are true. Experts can be asked to assume the existence of those facts and to express opinions that are based on those assumed facts. Those hypothetical questions are only proper, however, if a witness with personal knowledge has testified about the existence of the assumed facts.
Some courts do allow experts to testify about case-specific facts if they recite the mantra that experts in their field reasonably rely upon such facts to form opinions. Those courts often instruct juries that the hearsay facts should not be taken as true.
The California Supreme Court recognized the incongruity of an instruction that asks a jury not to accept as true the facts that an expert relies upon in forming an opinion. “When an expert relies on hearsay to provide case-specific facts, considers the statements as true, and relates them to the jury as a reliable basis for the expert’s opinion, it cannot logically be asserted that the hearsay content is not offered for its truth.” Since the jury will certainly regard the hearsay facts as evidence of the defendant’s guilt, those facts must be established by independent evidence.
Expert Testimony About Predicate Offenses
The state supreme court noted that it can be challenging to draw “the line of demarcation between background and case-specific information”. The court met the challenge rather easily. The court suggested that “information about gangs, like their territory, symbols, and operations” is admissible background information if the information is “generally accepted as true by experts in the field.” Whether two or more police officers who compare notes about their conclusions can create data that is “generally accepted as true by experts in the field” is a question the court did not address.
The court rejected reasoning from intermediate appellate decisions that distinguished “historical facts” about a gang’s conduct from “specific facts relating to the events and participants involved in the case being tried.” The gang statute requires those “historical facts” to be established as case-specific evidence. The specific crimes committed by specific members of a specific gang are not background facts that are “generally accepted” by other gang experts. They are facts known only to officers who investigated the specific crimes that are alleged as predicate offenses. Telling another officer about the results of a specific investigation of a crime does not make the investigation’s results “generally accepted” by all experts in gang behavior.
The supreme court recognized that prosecutors use “gang experts” to place evidence before the jury that the prosecutors cannot prove independently. The court put an end to that abusive practice by requiring evidence of predicate offenses to be established by the independent testimony of a witness with personal knowledge before the expert can rely on the existence of predicate offenses when the expert offers opinions.
The California Supreme Court’s decision draws a sensible line between background facts that may be part of an expert’s testimony, even if it is hearsay, and background facts that an expert can only testify about in response to a hypothetical question after the facts have been established by other witnesses. While the court’s decision may be compelled by the Confrontation Clause in some criminal cases, the reasoning is equally applicable to civil cases. Other state courts that struggle to understand when an expert can testify about otherwise inadmissible hearsay would benefit from reliance on the Valencia decision.